The correct option is D group
Collective nouns refer to a group of people, things or animals. In the given sentence, 'group' is a collective noun because it refers to a group of students. Hence option D is correct. 'Students' is a common noun, it denotes the plural form of the noun 'student', it's not a collective noun. Street is a common noun that refers to a general place, it's not a collective noun. Hence options A, B and C are incorrect.